Respuesta :

jerryguo2282769

Answer: the earth was just starting to develop really well and well enough for life.

Explanation: atmospheric oxygen and oceanic calcium levels went up, but nobody needs to know that much facts about how earth developed, But the group called phyla started growing because of these conditions

Lling123

Answer:

Explanation:

Tôi nghĩ rằng nếu quan trọng thời điểm đó phải là hình thành tầng ozon tạo tiền đề thiết lập hệ sinh thái